Pyrometer thermocouple



o. BROPHY PYROMETER THERMocoUPLE Filed March 27, 1923 F1a. 3. Y

Patented Dec. 6, 1927.

1,651,150 UNiTEn STATES PATENT oFFlcE.

OSCAR BROPHY, OF PHILADELPHIA, PENNSYLVANIA.

PYROMETER THERMOCOUPLE.

Application filedV March 27, 1923-. Serial No. 628,015.

. My invention relates to a protective coatstance which will not dissolve in the particular metal, the temperature of which is being' ing for a pyrometer thermocouple adapted for measuring high temperatures. My invention is adapted for thermocouples having two elements which are exposed to the heat and it is also particularly adapted for the type of pyrometer having a central element encased in a tubular element.

rlhe object of my invention is to provide means forprolonging the life of va pyrometer thermocouple, adapted for measuring the temperature of molten metal; a further object of my invention'is to apply the protective coating upon the outer surface of the elements of a thermocouple or upon the outer surface of the tubular' element of a thermocouple, thus avoiding the necessity of using a protective tube, or sheath, into which the thermocouple is usually encased when measuring the temperature of molten metal; and a still further object of my invention is to apply the protective coating directly upon the surface of the'thermocouple element, or elements, exposed to the high temperature and thus avoid any lag in the reading of the indicating instrument.

Referring to the accompanying drawing; Fig. 1, is a central longitudinal sectional view of my improved pyrometer thermo- 30 couple; Fig. 2, is a transverse section on line 2-2 Fig. 1, and Fig. 3, is a longitudinal sectional view o a different form of thermocouple.

In Figs. 1 and 2 of the drawing is shown a form' cfvpyrometer thermocouple 1, consisting of a central wire element 2, which is enclosed within a tubular element 3. The central element 2 is weldedat thepoint 4 to the tubular element 3. Said elements .are electrically connected with conductors 6 and 7, which are connected with a measuring instrument, (not shown in the drawing), adapted to indicate a dierence of potential in the circuit, ,when heat is applied to the thermocouple. Said difference of potential being caused by the action of heat upon the different metals, of which the elements 2 and 3 are formed, in a manner well known in the art. y

The present invention relates to the protective coating 8 formed upon the outer surface of the` tubular element 3. Said coating 8 extends; over the portion of. the tube 3 which is inserted into the molten metal.,

The coating 8 formed upon the tubular element 3 consists of a thin layer of a submeasured.

The metal coating 8 upon the tubular element 3 may consist of molybdenum, tungsten, ferromolybdenu'm, errotungstcn, or other suitable metal.

The method of applying the coating 8 upon the tubular element 3, consists of alloying, or combining chemically 'the metal forming' the coating 8, with the tubular element 3. For example, the tubular element 3, `which is -an iron tube, is coated with molybdenum and then subjected toA heat treatment, romolybdenum. Fi 3, of the thus forming a coating of ferent orm of pyrometer thermocouple, consisting of elements 10 and 12 of dierent metals, welded together at the portion 13, -which is adapted to be inserted into Athe molten metal. The protective coating 14 is applied to the surfaces of both elements 10 and 12, in the above described manner.

By my improved method of forming a protective coatin upon the element, or elements, of the t ermocouple, a very thin coating is formed thereon which will not appreciably retard the flow of heatto the welded juncture of the two elements of the lthermocouple, and the coating will protect said element, or elements, from deterioration due to 'the intense heat of the molten metal. He'retofore it has been the practice to encase the thermocouple in a protective sheath, ortube, which necessitated a small air space between the sheath, and the thermocouple.

heat from acting quick Said air space prevented the y upon the thermo- Having thus described my invention I claim and desire to secure by Letters Patent drawing illustrates a dier- 'gf .l I 1,651,750

1. A thermocouple adapted to loe imadapted to be immersed in molten metals, a

I mersedv in molten metals, a metallic coating metallic coating up'on the tubular element,

uponthe thermocouple, vsaid.' coating beingV said coating being integral with the metal 1 integral with the metal of vthe tliermocouple of the tubular element and insoluble in the 5 and insoluble in `said molten metals. molten metals.

2. A thermocouple, having a tubular ele In testimony whereof I aix mysignature. -ment and a second element enclosed therein, OSCAR BROPHY. 

